Methods and apparatus for managing pressurized gas in fluid dampers

ABSTRACT

A method and apparatus for a shock absorber having a damping fluid compensation chamber with a gas charge. In one aspect, a partition separates a first chamber portion from a second chamber portion, wherein the first portion of the chamber is at a first initial gas pressure and the second portion of the chamber is at a second initial pressure. A valve separates the first and second chamber portions and opening the valve comingles the first and second chamber portions so that the combined chamber portions are at a third pressure. In another aspect, a piston disposed through a wall is in pressure communication with the gas charge and is biased inwardly toward a pressure of the charge, whereby an indicator is movable by the piston in response to the pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of theco-pending U.S. patent application Ser. No. 16/159,403 filed on Oct. 11,2018, entitled “METHODS AND APPARATUS FOR MANAGING PRESSURIZED GAS INFLUID DAMPERS” by John Marking, assigned to the assignee of the presentapplication, having Attorney Docket No. FOX-0040US.CON3, and is herebyincorporated by reference in its entirety.

The application Ser. No. 16/159,403 claims priority to and is acontinuation of U.S. patent application Ser. No. 15/136,148 filed onApr. 22, 2016, now U.S. Issued U.S. Pat. No. 10,124,642, entitled“METHODS AND APPARATUS FOR MANAGING PRESSURIZED GAS IN FLUID DAMPERS” byJohn Marking, assigned to the assignee of the present application,having Attorney Docket No. FOX-0040US.CON2, and is hereby incorporatedby reference in its entirety.

The application Ser. No. 15/136,148 claims priority to and is acontinuation of the U.S. patent application Ser. No. 14/331,133 filed onJul. 14, 2014, now U.S. Issued U.S. Pat. No. 9,341,226, entitled“METHODS AND APPARATUS FOR MANAGING PRESSURIZED GAS IN FLUID DAMPERS” byJohn Marking, assigned to the assignee of the present application,having Attorney Docket No. FOX-0040US.CON, and is hereby incorporated byreference in its entirety.

The application Ser. No. 14/331,133 claims priority to and is acontinuation of the U.S. patent application Ser. No. 12/900,687, nowU.S. Issued U.S. Pat. No. 8,807,300, filed on Oct. 8, 2010, entitled“METHODS AND APPARATUS FOR MANAGING PRESSURIZED GAS IN FLUID DAMPERS” byJohn Marking, assigned to the assignee of the present application,having Attorney Docket No. FOXF/0040US, and is hereby incorporated byreference in its entirety.

The application Ser. No. 12/900,687 claims the benefit of and claimspriority to the U.S. Provisional Patent Application Ser. No. 61/267,646,filed Dec. 8, 2009, entitled “VISUAL GAS PRESSURE INDICATOR” by JohnMarking, assigned to the assignee of the present application, havingAttorney Docket No. FOXF/0041L, and is hereby incorporated by referencein its entirety.

The application Ser. No. 12/900,687 claims the benefit of and claimspriority to the U.S. Provisional patent application Ser. No. 61/254,947,filed Oct. 26, 2009, entitled “SELF CHARGING SHOCK” by John Marking,assigned to the assignee of the present application, having AttorneyDocket No. FOXF/0040L, and is hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to shock absorbers for vehicles. Moreparticularly, the invention relates to fluid dampers. More particularlystill, the invention relates to methods and apparatus for controllingand managing pressurized gas used in a fluid damper reservoir.

Description of the Related Art

Suspension systems (e.g. “shock absorber”) for vehicles, including motorvehicles and bicycles, include a spring portion and a damper portion.The spring portion creates resistance to a shock absorber's compression,and that resistance may increase non-linearly as the spring iscompressed. In some instances, springs are coil springs or leaf springsand in other instances they are gas springs that produce a non-linearcompression curve due to the compression of a given quantity of gas.Dampers, on the other hand, produce resistance as a piston moves throughsubstantially incompressible fluid, making the operation of the damperdependent upon shock absorber compression velocity rather than thestroke position of the suspension system. A fluid damper typicallyinvolves a chamber having a damping fluid disposed therein and a pistonand rod which together move in and out of the fluid chamber as thesuspension system compresses and rebounds. The piston is equipped withfluid passages, usually including shims, which restrict the flow offluid through the piston from one side of the chamber to the other andprovide the damping effect as the piston and rod move into and out ofthe chamber.

When the piston and rod enter the fluid chamber, a volume of fluid equalto the volume of the incoming piston rod must be displaced from thechamber. In order to compensate for the reduction in space for thefluid, a reservoir is used which typically consists of a floating pistonthat operates with a volume of gas behind the piston. As the volume inthe fluid chamber decreases, the floating piston moves against thevolume of gas which thereby becomes compressed. In this manner, thereservoir volume available for the damping fluid can increase anddecrease during each respective compression and retraction stroke of theshock absorber. A reservoir can be integrally included as a part of thedamper chamber or can be a separate chamber, usually adjacent the maindamper chamber.

In some instances, especially for larger capacity dampers used withmotor vehicles, it is not unusual to have the gas volume of the remotereservoir pressurized for use to 200 psi. Due to the physical size andweight of the damper and the tendency of the charged gas reservoir toextend the piston and rod, these shocks can be difficult to mount whenthe gas volume is charged with pressure, due to an individual'sinability to compress the rod and piston by hand. This problem has beenaddressed by providing the damper to the customer in a pre-chargedcondition, but with a strap or other temporary restraining memberretaining the damper in a partially compressed position. After thedamper is installed on a vehicle, the strap is removed to permit thedamper to extend to its fully extended position.

Because the gas pressure of the gas volume in a damper affects theoverall performance of the damper, maintaining appropriate gas pressureis important. In some instances, however, the mere act of checking thepressure results in a gas volume which is under-pressurized due to thesmall gas volume and the necessity of utilizing at least a small part ofthe gas while checking the pressure. Constant checking only exacerbatesthe issue and often results in an underpressured reservoir.

What is needed is a way to facilitate the installation of dampers onvehicles while ensuring that the damper will be provided with theappropriate gas pressure in the reservoir portion. Additionally, thereis a need for a safe and easy way to determine whether a gas volume in adamper is appropriately charged with the desired amount of gas pressure.

SUMMARY OF THE INVENTION

The present invention generally comprises a damper having a dampingfluid compensation chamber, or reservoir, with a gas charge. In oneaspect, a partition separates a first chamber portion from a secondchamber portion, wherein the first portion of the chamber is at a firstinitial gas pressure and the second portion of the chamber is at asecond initial pressure. A valve or frangible member separates the firstand second chamber portions and opening the valve comingles the firstand second chamber portions so that the combined chamber portions are ata third pressure based on their respective initial pressures andvolumes. In another aspect, a piston disposed through a wall of theshock absorber is in pressure communication with a reservoir gas chamberand is biased inwardly toward an interior volume of the chamber, wherebyan indicator is movable by the piston (or comprises the piston) inresponse to a gas pressure in the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features can be understoodin detail, a more particular description, briefly summarized above, maybe had by reference to embodiments, some of which are illustrated in theappended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a section view of a damper h a remote reservoir.

FIG. 2 is a section view of the remote reservoir of FIG. 1 showingpre-charge assembly.

FIG. 3 is a section view of the remote reservoir of FIG. 2, with thepre-charge assembly in a shifted position.

FIG. 4 is a section view of a remote reservoir showing a gas pressureindicator.

FIG. 5 is a section view of the remote reservoir of FIG. 3 with thepressure indictor incorporated therein.

DETAILED DESCRIPTION

FIG. 1 is a section view of a fluid damper 100 embodiment, typically fora motor vehicle. The main parts for the damper include a fluid chamber105 and a rod 110 with a piston 115 disposed at the end thereof forextending into the fluid chamber 105, thereby dividing the chamber intocompression and rebound portions respectively on opposite sides of thepiston 115. In FIG. 1, the rod and piston are shown in their fullyextended position as they would appear at the beginning of a compressionstroke (e.g. an uncompressed damper). The damper also includes a remotereservoir 125 or compensation chamber, constructed and arranged toreceive damping fluid via a communication, or fluid flow, path 130. Theremote reservoir is divided into a damping fluid 135 and a compressedgas portion 150 with the two portions separated by a floating piston 155which, as described herein, is sealed with an O-ring 230 and movesagainst the volume of compressed gas in the gas portion 150 as fluiddisplaced from the fluid chamber 105 during a compression stroke of thedamper moves into the fluid portion 135 of the remote reservoir 125.

In one embodiment the damper of FIG. 1 is often installed as part of avehicle suspension system and a mounting lug or “eyelet” 160 formed atan end of Inc fluid chamber is connected to Inc vehicle frame whileanother mounting lug 162 disposed at an end of the rod is attached tothe vehicle wheel (not shown). As the damper operates, the piston 115and rod 110 move into and out of the fluid chamber 105, metering fluidthrough communication paths 170 and shims in the piston. An annularbumper 175 is disposed at an end of the piston rod 110 to prevent theassembly 100 from reaching a bottom-out condition.

In addition to the components of the damper described, the damper ofFIG. 1 includes a pre-charge assembly 200 disposed at an end of theremote reservoir 125 (note that if the reservoir were in line with thedamper so to would be such a pre-charge assembly). The pre-chargeassembly includes a pre-charge gas portion 210 which is separated fromthe compressed gas portion 150 of the remote reservoir 125 by apartition 215. The assembly 200 also includes a fill/communication valve220 constructed and arranged to permit initial charging of thepre-charge gas portion and to allow a user to permit fluid communicationbetween the pre-charge portion 210 and the compressed gas portion 150.

FIG. 2 is a section view of the pre-charge assembly 200 of FIG. 1. Inthe embodiments of FIGS. 1 and 2, the assembly 200 is located at one endof the remote reservoir 125 of the damper 100 and the pre-charge portion210 houses a volume of pressurized gas which is retained between an endcap 225 and partition 215. Both the end cap and the partition are sealedwith O-rings 230 or other suitable seals and each is retained axially bystructural rings 235 acting against shoulders 240 formed in the cap 225and partition 215 to maintain structural integrity against the highlypressurized gas (e.g. 600-800 psi in one embodiment) that will be housedin the pre-charge portion 210. In one embodiment, the compressed gasportion 150 is isolated from the pre-charge portion and gas pressure inportion 150 is limited to atmospheric pressure. The gas pressure inportion 150 may be any suitable low pressure, preferably such that thenet extension force acting on rod 110 due to the pressure may beovercome manually.

Disposed in the pre-charge assembly is a fill/communication valve 220intended to facilitate initial filling of the pre-charge portion 210 andto provide selective communication between the pre-charge portion 210and the compressed gas portion 150 of the remote reservoir. Thereafter,the valve 220 provides a way to further fill or adjust the combined gasportion of the reservoir with pressurized gas. The valve is shown with aprotective cap 245 threaded onto an end thereof.

The fill/communication valve 220 includes a central member 250 havingexternal threads 255 which interact with internal threads 260 formed inthe end cap 225, whereby rotation of the central member 250 providesaxial movement (corresponding to the thread pitch) of the communicationvalve 220 relative to the end cap 225. The central member 250 includes aseal 230 at each end of the threaded portions 255, 260. In oneembodiment the cap gland interior seal 230 engages a relatively smoothouter diameter of the central member 250 and seals initial pressure ofthe pre-charge portion 210 prior to movement of the central member 250and corresponding gas commingling between the pre-charge portion 210 andthe compressed gas portion 150. An interior portion 265 of the centralmember is hollow and a first communication path including apertures 270is formed between the hollow portion of the central member 250 and thepre-charge portion 210 therearound. For example, in FIG. 2, gascommunication exists only between the pre-charge portion and the centralmember (permitting the pre-charge portion to be initially chargedwithout introducing gas pressure elsewhere). A second communication pathapertures 275 extending from the interior portion 265 of the centralmember is blocked in the position shown in FIG. 2. The result is that inthe position of FIG. 2, there is no fluid communication from thepre-charge portion to any other operative portion of the damper 100(i.e. the pre-charge is isolated by the central member 250 and thepartition 215.

FIG. 3 is another section view of the pre-charge assembly 200 of FIG. 2showing the central member 250 in a shifted position, whereby fluidcommunication, illustrated by arrows 280, is permitted between thepre-charge portion 210 and the compressed gas portion 150 of thereservoir 125 (via apertures 270, bore 265 and apertures 275). Thepre-charge assembly 200 has been shifted by rotation of the centralmember 250 to provide axial movement of the fill/communication valverelative to the end cap 225 and relative to the partition 215. In theposition shown in FIG. 3, compressed gas flows through the firstcommunication path, through the interior portion 265 of the centralmember and exiting the second communication path 275 which has beenplaced into fluid communication with the compressed gas portion 150.Once communication is complete, portions 210 and 125 are combined toeffectively form a single larger-volume gas portion at a pressurecorresponding to a volume weighted combination of the pressures of thepre-charge and the compressed gas portions.

In one embodiment, partition 215 comprises a rupture disk or frangiblemembrane. The membrane contains the pre-charge pressure under initialcircumstances with the central member in its initial position. In suchan embodiment an end of the central member is proximate the partitionbut does not necessarily penetrate it. The central member includes arelatively sharp end (end near apertures 275) that is capable ofpiercing the partition upon axial movement of the central member. Thecentral member is axially moved toward the membrane as described hereinfor in other suitable fashion) and the sharp end of the central memberpierces the partition thereby communicating the pre-charge portion gaswith the compressed gas portion gas. That results in gas commingling asdescribed herein.

Because the operational reservoir pressure (e.g. the combined pressureof the pre-charge and the compressed gas portions) is initially isolatedfrom the active portions of the damper, the rod and piston length can beeasily adjusted (for example manually) for installation. Once the damperis installed between mounting points in a vehicle, the central member ofthe fill/communication valve is threaded inwards, placing the secondcommunication path apertures 275 in communication with the compressedgas portion of the damper, thereby permitting gas communication betweenthe portions. In one aspect, the pre-charge assembly 200 is utilizedwhereby an end user receives a damper with effectively no gas pressureacting upon the floating piston in the remote reservoir and hence nopressure acting on an end area of the piston rod 110. In fact, the gaspressure (a higher pressure designed to be commingled at a lowerequilibrium pressure) is all stored in the pre-charge portion 210 of thereservoir. With this arrangement, the piston and rod are easilymanipulated back and forth in the fluid chamber which facilitatesmounting of the damper relative to mounting locations on the vehicle.Thereafter, the pre-charge assembly is shifted and the damper operatesnormally utilizing the combined gas portions 210, 125 as a single gasvolume.

In one example, the fluid damper is intended to operate with 200 psi inthe compressed gas portion of the remote reservoir 125. In oneembodiment, 800 psi of pressure is placed into the pre-charge portion.Once the damper is installed and the pre-charge portion shifted, thevolume of pre-charge gas at 800 psi commingles with the volume of thecompressed gas reservoir at atmospheric pressure resulting in 200 psi isavailable throughout the reservoir for normal operation in the damper.While the central member 250 is no longer needed to permit or restrictcommunication between the portions, the fill/communication valve 220(e.g. Schader type) operates as a fill valve to check and maintainrequired gas pressure in the remote reservoir 125 throughout the life ofthe damper.

FIG. 4 is a section view of a compressed gas portion 150 of a remotereservoir 125 having a gas pressure indicator assembly 300. As describedwith reference to the other embodiments of the invention, the compressedgas portion 150 shown in FIG. 4 is part of a remote reservoir thatoperates with a floating piston (not shown) acting against a source ofpressurized gas to provide increasing and decreasing volume for fluiddisplaced from a main fluid-filled dampening chamber. Shown in FIG. 4 isan end of the reservoir housing 305, an end cap 225 that is sealed withO-rings 315 and retained with structural rings 235, a fill valve 310with a cap 311 for communicating pressurized gas into the compressed gasportion 150 and the gas pressure indicator assembly 300. The purpose ofthe assembly 300 is to provide a visual indicator of the gas pressure inthe gas portion.

Gas pressure indicator assembly 300 includes a shaft 315 with a pistonsurface 320 formed at a first end and exposed to the interior of the gasportion 150, whereby pressurized gas in the gas portion acts upon pistonsurface 320. The shaft 315 is sealed in an aperture 330 formed in endcap 225 and sealed with O-ring 230. The shaft and piston surface arebiased towards the interior of the housing by a spring 325. Opposite thepiston surface is an indicator 340 constructed and arranged to bevisible only when the shaft/piston surface are depressed against thespring 325 hence allowing 340 to extend beyond a surface of cap 225. Inuse, the assembly 300 is designed whereby the spring 325 is overcome andthe piston 320 is depressed when a predetermined pressure exists in thegas portion 150 of the reservoir. Such a position is shown in FIG. 4with the shaft 315 urged in direction of arrow 316 and the indictor 340in an extended position where it would be visible to a user. Instead ofchecking the pressure with a gauge and depleting the gas portion ofpressure in doing so (because a pressure gauge requires a volume of thegas being testing and consumes that volume for each test instance), theindicator provides visual assurance of the presence of a certain minimumamount of gas pressure.

FIG. 5 is a section view of the remote reservoir 125 of FIG. 3 withpressure indicator assembly 300 incorporated therein. The pre-chargeassembly 200 with its pre-charge portion 210 operates as described withreference to FIGS. 1-3 wherein the pre-charge portion retains theworking gas pressure until an end user manipulates a fill/communicationvalve 220 to permit fluid communication between the pre-charge portion210 and the compressed gas portion 150 (as described herein).Thereafter, the reservoir functions normally with a predetermined gaspressure available in both portions and both portions combined andfunctioning as one, larger volume compressed gas portion. Also includedis the gas pressure indicator assembly 300. In the embodiment shown inFIG. 5, a portion of the shaft 315 including the piston surface 320 isextended to communicate with the compressed gas portion 150 of thereservoir. The pre-charge portion 210 does not act axially on the shaft315 because the shaft 315 runs entirely though the portion 210 andprotrudes through each end with a diameter equal at each end (i.e. nonet piston area on shaft 315 vis a vis volume of portion 210). In oneembodiment the arrangement shown in FIG. 5 operates as described hereinregarding selective commingling of a pre-charge 210 and a gascompression chamber 150. In the embodiment of FIG. 5 the indicator shaftis moved when compressed gas of portion 150 acting on piston area 320overcomes spring 325 force. As such the indicator provides a visualindication that commingling has been successful following movement ofthe central member. In this manner, the indicator 340 not only providesa visual indicator of working gas pressure in the reservoir, but isuseful in confirming that initial communication has taken place betweenthe portions 210, 150 after manipulation of the central member. In FIG.5, the pressure indicator 340 is shown in its extended positionindicating the presence of at least a minimum amount of pressure in thecompressed gas portion 150.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What we claim is:
 1. A damper for use with a suspension system, thedamper comprising: a fluid-filled chamber for receiving a piston androd; a remote reservoir in fluid communication with the chamber, theremote reservoir having a fluid portion and a compressed gas portion,said compressed gas portion having a gas disposed therein; a floatingpiston disposed between said fluid portion and said compressed gasportion; a pre-charge assembly disposed at an end of the remotereservoir, said pre-charge assembly comprising: a pre-charge gasportion; a partition, said partition disposed separating said pre-chargegas portion from said compressed gas portion of said remote reservoir;and a fill/communication valve coupled to said pre-charge gas portion;said fill/communication valve configured to and to adjust a pressure ofsaid pre-charge gas portion and allow a user to permit fluidcommunication between said pre-charge portion and said compressed gasportion; an end cap, said end cap disposed at an end of said remotereservoir such that said compressed gas portion is disposed between saidend cap and said floating piston; and a gas pressure indicator assemblycoupled to said compressed gas portion; said gas pressure indicatorassembly configured to provide a visual indication of said gas pressurein said compressed gas portion.